John Neil Stewart Simpson was born in Longcroft, Stirlingshire, Scotland. He graduated from the Glasgow School of Architecture in 1958. He moved to Canada in 1963. He worked as an architect and then founding partner with John Andrews Architect in Toronto from 1963 until 1972 before becoming founding director of the Australian-based practice of John Andrews International (1972-1983).

After settling in Brisbane in 1983 he founded John Simpson Associates Pty Limited (1983-1995), also known as JSA. JSA designed the River Stage for Expo 88 in Brisbane, and the Entertainment Piazza for the South Bank Corporation in 1991. His work for The University of Queensland included the Hawken Engineering Building, the General Purpose Social Sciences Building, the Chemical Engineering Building, the Ritchie Research Laboratories and the Sir Zelman Cowan Building. From 1995, as John Simpson Architect, Simpson specialised in strategic and tactical architectural planning and urban design services. In this period he was appointed master planner for Brisbane’s South Bank. In 1997 Simpson was awarded the silver medal for Queensland Architect of the Year, and in 2000 was granted life fellowship of the Royal Australian Institute of Architects. John Simpson holds honorary doctorates from Queensland University of Technology and The University of Queensland.

John Simpson Associates Pty Limited (1983-1995), also known as JSA, formed in 1983 until it was taken over by Spowers in 1996. Architects that formed part of JSA included: John Simpson, Ian Mitchell, and Dereck Wheeler.